Circuit interrupter



April 20, 1948.

WITNESSES:

A. P. STRQM 2,439,952

CIRCUIT INTERRUPTER Filed Aug. 31, 1.944

4 Sheets-Sheet l Non-Mayne f/c M0gne f/c fVon- Magnef/c M0 fer/a/ I Magnef/c Ma fer/a/ 2/ 2/ W017 Mag/7e M0 fer/a/ INVENTOR AVberf P Sfrom Z2 BY g/ a a ATTORNEY April 20, 1948. A. P. STROM CIRCUIT INTERRUPTER Filed Aug. 31. L944 4Sheets-Sheet 2 Magnef/c Ma fer/o/ m R mm m l W m mP/ n M A mm G m W m Maw m April 20, 1948. STROM 2,439,952 CIRCUIT INTERRUPTER Filed Aug. 31, L944 4 Sheets-Sheet 5 A/an- Mag/1677c Mafer/a/ 5 S Mayne/[c Maier/bl IN V ENTOR A/beri P. 5770/77 q BY 2/ 2 ATTORNEY Patented Apr. 20, 1948 CIRCUIT INTERRUPTER Albert P. Strom, Forest Hills,

Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 31, 1944, Serial No. 552,064-

8 Claims. 1

This invention relates to circuit interrupters in general and, more particularly, to arc-extinguishing structures therefor.

The use of a magnetic field to move or spin the arc in a circuit interrupter around some path between the open contacts has been found to be beneficial since it reduces contact burning and generally also increases the voltage or current that can be interrupted. Such a construction is shown in United States Patent 2,333,598 which was issued to me on November 2, 1943, and which was assigned to the assignee of the instant application.

In the aforesaid patent, an arc is established between cooperable ring-shaped electrodes and is rotated therearound by a radial magnetic field while being simultaneously subjected to either a radial outward or inward gas blast. However, when magnetic spinning is applied to an interrupter in which flow of the liquid or gas interrupting medium also occurs, undesirable eifect-s are encountered under some conditions due to are looping. In the case of tubular contacts with radial now, the arc may be pushed along by the flow into an elongated bow so that whereas the distance between contacts may be only a fraction of an inch, the arc length may actually be many times this contact separation. Consequently, the main body of the are is no longer perpendicular to the field, but almost parallel to it, and hence has only a very feeble force tending to maintain its spinning motion. In some cases, part of the arc may move entirely out of the main field. Uncontrolled elongation of the arc is further undesirable since it raises the arc voltage during the portion of the half cycle when current is large, and hence increases the energy available to decompose and expand the interrupting medium, and also to erode the contact surfaces.

One solution for the above problem is presented in a patent application by Winthrop M. Leeds, Serial No. 549,575, filed August 15, 1944, and assigned to the assignee of this invention. This patent application describes and claims structure employing a longitudinal flow of fluid coupled with a rotating arc to thereby prevent bowing of the are out of the magnetic field.

My invention describes types of circuit interrupters in which negligible arc looping should occur, even when both flow and magnetic spinning are employed. This is accomplished by dividing the flow passage by a plurality of arc terminal members into a plurality of passages so narrow that heavy current arcs will not loop thereinto.

The general object of my invention is to provide an improved circuit interrupter in which interruption of the circuit passing therethrough is accomplished more effectively than heretofore.

Another object is to provide an improved circuit interrupter in which the cooperable electrode structure consists of a plurality of annular spaced arc terminal members between which the established arc is rotated by a magnetic field. Preferably, a fluid blast, either gaseous or liquid, is forced through the electrode structure to subject the rotating arc to a fluid blast substantially longitudinally of its length.

Further objects and advantages will readily become apparent upon a reading of the following specification taken in conjunction with the accompanying drawings, in which:

Figure 1 is a vertical sectional view of a circuit interrupter embodying my invention, taken substantially on the line 1-1 of Fig. 2, the parts being shown in the partially open circuit position;

Fig. 2 is a sectional View taken along the line II-lf'f of Fig. 1;

Fig. 3 is a sectional view taken along the line III-J11 of Fig. i;

Fig. 4 is a sectional view taken along the line Iii-IV of Fig. 1.;

Fig. 5 is a plan view of the modified type of circuit interrupter shown in Fig. 6 and taken substantially along the line V--V of Fig. 6;

Fig. '3 is a vertical sectional view of a modified type of circuit interrupter taken along the line VIVI of Figs. 5 and '2, the parts being shown in the partially open circuit position;

Fig. '2 is a sectional view taken substantially on the line VII-VII of Fig. 6; and

Fig. 8 is a. perspective view of a magnetic yoke member used in the construction of the circuit interrupter shown in Fig. 6.

Referring to the drawings, and more particularly to Fig. 1 thereof, the reference numeral l designates an insulating tubular casing in which is fixedly secured the stationary electrode structure or fluid exhaust electrode generally designated by the reference numeral 2. In this instance, the electrode structure 2 comprises a plurality, in this instance three, spaced conducting tubes or annular arc terminal members 3, 4 and 5 concentrically positioned within the casing I having fluid exhaust passages therebetween. The conducting tubes 3, 4 and 5 are maintained in position by being inserted in recesses 6 provided in a conducting web member I, the latter being secured to the casing I by a bolt 8 and nut 9. Preferably, the web member I and the tubes 3, 4 and are composed of a non-magnetic material, such as copper or brass.

Threadedly secured at III to the web member I is a magnet core composed of a suitable magnetic material, in this instance iron, and having an insulating plug l2 suitably secured at the lower end thereof to prevent a terminal end of the are from attaching thereto.

Disposed about the casing is a field coil l3 comprising a winding of copper strap more clearly shown in Fig. 3. Also, surrounding the casing at the lower end thereof is a second field coil l4 having a winding of copper strap and producing a magnetic field opposed to the field produced by the field coil I3, such that a radial magnetic field is established between the stationary electrode structure 2 and the movable electrode structure or fluid entrance electrode generally designated by the reference numeral l5. In this instance, the electrode structure l5 comprises a plurality of, in this instance two, spaced. conducting tubes or annular arc terminal members I6, I! suitably secured in recesses l8 provided in a movable web member I9 having a fluid entrance passage provided therebetween. The web member l9 in this instance forms an integral part of a conducting cylinder 20 actuated by a web structure 2| also integrally formed therewith. Amovable insulating operating rod 22 threadedly secured at 23 to the web structure 2| causes actuation of the same. Preferably the tubes I6, I! and parts I9,

Suitable means, not shown, may eflect an initiation of the fluid blast and a stoppin thereof following extinction of the are 29.

While it is highly desirable to keep heavy current arcs as short as possible, it may be desirable to let the upper terminal of small current ares move up between the concentric tubes 9. 4 and 5 on theoutlet side of the arc region. This action is permitted by this construction because large currents tend to restrike at the lower edges of the concentric tubes 3, 4 and 5, whereas small current arcs may lengthen somewhat before restriking. The spacing between the tubes 9, 4 and 5 may be limited to between 1 6 and inch to prevent .travelof heavy current are terminals up between the electrode cylinders 3, 4 and 5. 0n the inlet side the spacing between the tubes i6 and I! may be wider since there is no tendency for the arc .terminal to move against the fluid flow. The discharge area between the concentric tubes 3, 4 and'5 on the discharge side of the are region should be sufllciently small, as compared to the inlet area between tubes I6, I1, and easing I, so that a considerable part of the fluid pressure, especially where a gaseous fluid is employed, is maintained in the arcing region, in order to maintain high dielectric strength in the are region. I;

In the embodiment of my invention shown in Figs.- 5 through 8, it will be observed that I have coil l4, strap 25, stud 26, flexible conductor 21,

conducting cylinder 20, movable electrode structure l5, cooperable stationary electrode structure 2, web member 1, bolt 8, field coil 13 to theterminal strap 28. To open the electrical circuit passing through the interrupter, the operating rod 22 is moved downwardly to cause a separation between the conducting tubes I6, I I from the stationary conducting tubes 3, 4 and 5 to draw an are 29. The radial magnetic field set up by the field coils l3 and I4 indicated by the dotted lines 3|l3| causes a rotation of the are 29 about the cooperable electrode structures.

.to a fluid blast substantially longitudinally of its length. As mentioned previously, the insulating plug 2 prevents an establishment of a terminal end of the arc on the magnetic core Similarly, an insulating plug 32 prevents the establishment of the other terminal end of the are 29 to an end of the magnetic core 33 threadedly secured at 34 to the web member l9.

If desired, apertures 35 may be provided in the conducting tubes to more effectively direct the fluid blast adjacent the rotating are 29. The rotation of the are 29 continues until it is extinguished. It will be observed that the fluid blast is longitudinally of the are 29 and consequently does not tend to force it to assume a bowed shape as was the case in the aforesaid Patent 2,333,598.

To efiect a closure of the contact structure to reestablish the electrical circuit passing therethrough the operating rod 22 is merely moved upwardly by suitable means, not shown, to cause a reengagement between the conducting tubes.

provided an insulating tube 38 having threadedly secured at 39 adjacent its upper end an insulating ring-shaped plate 40. Screws 4| secure a conducting ring 42 to the plate 40. The stationary or outer fluid exhaust electrode structure 49 in this instance comprises a plurality of, in this instance four, spaced ring-shaped conducting plates or annular arc terminal members 31, 44, 45 and 46, secured in position by a plurality, in

- this instance eight, screws 41 which pass through an insulating disc 53. Washers 48 mounted on the screws 41 serve to, space the plates to provide fluid exhaust passages therebetween.

Disposed above the disk 53 and below the insulating ring-shaped plate 49 are two soft iron rings 51 which serve to uniformly distribute the flux of a transverse magnetic field between the electrode structure set up by field coils generally designated by the reference numerals 59 and 59. Associated with the field coils 58, 59, being formed by two pancake coils, are a plurality, in this instance eight, magnetic yoke members generally designated by the reference numeral 69. The configuration of the yoke member 60 is more clearly shown in Fig. 8. Referring to this figure, it will be noted that the yoke member comprises -an L-shaped portion 6| and a clamping portion 62 secured to the L-shaped portion 6| by a screw 63.

The several yoke members 60 also serve to hold in position the field coils 58, 59. Outside of the soft iron rings 51 are insulating ringshaped plates 64, 65.

The movable or inner fluid entrance electrode structure 66 comprises a plurality of, in this instance two, ring-shaped'conducting plate members or annular arc terminal members 61, 59 secured in position by extensions 69, in this instance forming integral portions of a conducting cylinder member 10. The extensions 59 form supporting shoulders 1| upon which rest a ringshaped conducting plate member 68. A segmental spacer member I2 spaces the ring-shaped plate member 68 from the otherring-shaped plate member 81 to provide a fluid entrance passage therebetween. Above the plate 81 is a second spacer 13. A screw 14 passes through the two spacer members 12, I3, through the two plate members 81, 88 and has its lower end threadedly secured at 15 to the extension 89.

A conducting operating rod I8 is threadedly secured at H to a web structure 18, in this instance forming an integral portion of the cylindrical member 18.

The operation of this embodiment of my in vention will now be explained. In the closed circuit position, the electrical circuit passing through the interrupter comprises the terminal strap 18, conducting ring 42, ring-shaped conducting plate member 68, extensions 88, cylindrical member 18, web structure I8 to conducting operating rod 18. Thus, in the closed circuit position of the interrupter, both field coils 58 and 58 are shorted out, the ring-shaped plate 88 engaging in abutting relation the conducting ring 42.

To open the electrical circuit through the interrupter, the operating rod 18 is moved upwardly by suitable actuating means, not shown, thereby causing a separation between the ringshaped plate 88 and the conducting ring 42. This establishes an arc, the initial terminal positions of which are at the points 83, 84. The fluid blast, passing upwardly through the cylindrical member 18 and radially outwardly between the cooperable electrode structure, carries the arc which was initially established between the points 83, 84 to a position between the lower conducting ring 88 and the ring-shaped plate 31.

Now, however, the two field coils 58, 58 are brought into series circuit. In other words the electrical circuit now passing through the interrupter comprises terminal strap 18, strap 81, lower field coil 59, strap 88, strap 89, upper field coil 58, strap 90, washer 8i, screw 41, stationary electrode structure 43, are 82, movable electrode structure 68, conducting cylinder Hi to conducting operating rod '76.

The transverse magnetic field set up between field coils 58, and indicated by the dot and dash line 85, causes rotation of the are around the opposed peripheries of the ring-shaped plates tili, 58. During this rotation of the are 82, it is simultaneously subjected to a radially outward fluid blast which passes upwardly through the cylindrical member Til and radially outwardly between the extensions 68 and outwardly between the magnetic yoke members Bil. The rotation of the are 82 continues until it is extinguished.

To complete the electrical circuit through the interrupter, it is merely necessary to move the conducting cylindrical member I8 downwardly by the operating rod 18 until the ring-shaped plate 88 strikes the conducting ring 42 in abutting relation, thereby completing the electrical circuit through the interrupter and shorting out the field coils 58 and 59. Suitable means, not shown, may effect an initiation and a ceasing of the fluid blast. The conducting rings 44, 45, 48 and 31 on the discharge side of the arcing region should be spaced sufliciently close together so that the high current arc terminals will not readily travel down between them. While it is highly desirable to keep heavy current arcs as short as possible, it may be desirable-to let the terminal ends of the small current arcs move outwardly between the ring-shaped plates 81, 44, 48 and 58- on the outlet side of the arcing region. This action is permitted by the disclosed construction because large current arcs tend to restrike at the inner peripheries of the ringshaped plates 31, 44, 45 and 46; whereas small current arcs may lengthen somewhat before restriking. The proper spacing between the ringshaped plates 31, 44, 45 and 46 should be limited to between and A; inch to prevent travel of heavy current are terminals outwardly between the ring-shaped plates 31, 44, 45 and 45. On the inlet side of the arcing region, the spacing between the ring-shaped plates 81 and 68 may be wider since there is no tendency for the arc terminal to move against the fluid flow.

The discharge area between the ring-shaped conducting plates 31, 44, 45 and 48 on the discharge side of the arcing region should be sufilciently small as compared to the inlet area so that a considerable part of the fluid pressure, especially where a gaseous fluid is employed, is maintained in the arc region, in order to maintain high dielectric strength in the arc region.

For low current values the proper spacing 0n the outlet side would be in order of 1*; inch. For high current values this spacing would be slightly more, that is, ,4; inch.

Another arrangement for creating a transverse magnetic field between the stationary electrode structure 43 and the movable electrode structure 88 would be to eliminate the field coils 58, 59 and to magnetize the magnetic yoke members 88, in effect converting the magnetic yoke members 88 into a plurality of permanent magnets. If such a construction were used, the coils 58, 59 could be eliminated together with the disclosed arrangement for shorting out said field coils. This arrangement is, however, not disclosed in the drawings.

The magnetic field is provided to give a field perpendicular to the are 82 and hence to cause it to move rapidly around the concentric arc gap. With this construction, a very short air gap can probably be used if superimposed pressure is used to increase the dielectric strength of the gas. it is believed that about 100,000 R. M. S. restored volts per inch arc length can be interrupted with 10' atmospheres back pressure. Arc energ is thus reduced to a low value. Contact burning is negligible if the field moves the are 82 rapidly around the contacts.

I have tested a circuit interrupter of the type shown in Fig. i, using oil as the interrupting fluid. The performance indicated absence of arc looping since arc voltages were much lower than with the transverse fluid flow. The outside insulating tube diameter was 2% inches, and the contact separation was 0.5 inch. Interruptions were good at currents up to 2,000 amperes at 13.8 kv. The need for a large exit area to handle large currents in oil may be avoided by utilizing high pressure gas flow as the interrupting fluid.

From the foregoing description, it will be apparent that I have provided a circuit interrupter which produces a rotation of the arc to minimize contact burning and increase cooling and deionization; and that in conjunction with such a rotation I have employed a longitudinal fluid blast, either gaseous or liquid, to more readily eifect arc extinction, but yet preventing lengthening or bowing of the arc out of the magnetic field.

Although I have shown and described specific structures, it is to be clearly understood that the same were merely for the purpose or illustration and that changes and modifications may readily be made therein by those skilled in the art without fluid entrance passage therebetween, said annular arc terminal members of the two electrodes having their larger surfaces and the passages therebetween extending in substantially the same direction and having their edge portions facing each other at all times, and said edge portions providing an arc gap between the two electrodes during interruption of the circuit, means for establishing an arc which plays in the gap between the facing edges of the spaced annular arc terminal members, magnetic means for rotating the are around the arc gap between the edges of the spaced annular arc terminal members of the two electrodes, and means for causing a flow of fluid which flows without major change of direction while flowing through the spaces between the annular members of the entrance electrode, longitudinally of the arc across the arc gap and through the spaces between the annular members of the exhaust electrode.

2. In a circuit interrupter of the fluid blast type, a fluid exhaust electrode including a plurality of spaced annular arc terminal members all at one potential and having a fluid exhaust passage therebetween, a fluid entrance electrode including a plurality of spaced annular arc terminal members all at one potential and having a fluid entrance passage therebetween, said annular arc terminal members of the two electrodes having their larger surfaces and the passages therebetween extending in substantially the same direction and having their edge portions facing each other at all times, and said edge portions providing an arc gap between the two electrodes during interruption of the circuit, means for establishing an arc which plays in the gap between the facing edges of the spaced annular arc terminal members, magnetic means for rotating the are around the arc gap between the edges of the spaced annular arc terminal members of the two electrodes, a housing in which said entrance and exhaust electrodes are mounted in spaced relation to the housing to provide fluid flow passages between the outer of a plurality of said annular arc terminal members of each electrode and the housing so that fluid may flow on opposite sides of each of a plurality of said annular arc terminal members and longitudinally on opposite sides of the are in the gap between the facing edges of the annular arc terminal members of the two electrodes, and said passages between and outside of said annular arc terminal members of both electrodes extending in the same general direction so that the fluid may flow smoothly past both electrodes and longitudinally of the arc gap therebetween without substantial change in direction.

3. In a circuit interrupter of the fluid blast type, a fluid exhaust electrode including a plurality of spaced annular arc terminal members all at one potential and having a fluid exhaust passage therebetween, a fluid entrance electrode including a plurality of spaced annular arc terminal members all at one potential and having a fluid entrance passage therebetween, said annular arc terminal members of the two electrodes having 8 1 their larger surfaces and the passages therebetween extending in substantially the same direction and having their edge portions facing each other at all times, and said edge portions providing an arc gap between the two electrodes during interruption of the circuit, means for establishing an are which plays in the gap between the facing edges of the spaced annular arc terminal members, magnetic means for. rotating the are around the arc gap between the edges of the spaced annular arc terminal members of the two electrodes, means for causing a flow of fluid which flows without major change of direction while flowing through the spaces between the annular members of the entrance electrode, longitudinally of the arc across the arc gap and through the spaces between the annular members of the exhaust electrode, and the width of the spaces between the annular arc terminal members of the type, a fluid exhaust electrode including a plurality of spaced concentrically disposed conducting tubes all at one potential having one or more fluid exhaust passages provided therebetween, a fluid entrance electrode including a plurality of spaced concentrically disposed conducting tubes all at one potential having a fluid entrance passage provided therebetween, the tubes of both electrodes extending in substantially the same direction and the ends of the tubes of one electrode facing the ends of the tubes of the other electrode at all times, means for establishing an are between the facing ends of the two electrodes, magnetic means for rotating the are around the facing ends of the two electrodes, means for subjecting the rotating arc to a longitudinal blast of fluid which passes through the fluid entrance passage provided by the fluid entrance electrode, longitudinally adjacent the rotating arc and out through the one or more fluid exhaust passages provided by the fluid exhaust electrode, the spacing between the tubes of the fluid exhaust electrode being small to aid in keeping the terminal of high current are from being carried by the fluid blast into the spaces between the tubes.

5. In a circuit interrupter of the fluid blast t pe, a fluid exhaust electrode including a pinrality of spaced concentrically disposed conducting tubes having one or more fluid exhaust passages provided therebetween all at one potential, a fluid entrance electrode including a plurality of spaced concentrically disposed conducting tubes having a fluid entrance passage provided therebetween all at one potential, the tubes of both electrodes extending in substantially the same direction and have the facing ends of the tubes of the two electrodes in butt engagement when the interrupter is closed, and one of the electrodes being movable out of abutting engagement to establish an are between the facing ends of the two electrodes during the opening operation, magnetic means for rotating the are around the electrodes. means for subjecting the rotating arc to a longitudinal blast of fluid which passes through the fluid entrance passage provided. by the fluid entrance electrode, longitudinally adjacent the rotating arc and out through the one or more fluid exhaust passages provided by the fluid exhaust electrode.

6. In a circuit interrupter of the fluid blast type, a fluid exhaust electrode including a plurality of spaced concentrically disposed conductin: tubes all at one potential having one or more fluid exhaust passages provided therebetween, a fluid entrance electrode including a plurality of spaced concentrically disposed conducting tubes all at one potential having a fluid entrance passage provided therebetween, the tubes of both electrodes extending in substantially the same direction and having their adjacent ends facing each other. means for establishing an are between the facing ends of the two electrodes, magnetic means for rotating the are around the electrodes, means for subjecting the rotating arc to a longitudinal blast of fluid which passes through the fluid entrance passage provided by the fluid entrance electrode, longitudinally adjacent the rotating arc and out through the one or more fluid exhaust passages provided by the fluid exhaust electrode, the spacing between the tubes of the fluid exhaust electrode being between a; and /8 inch.

7. In a circuit interrupter of the fluid blast type. an outer electrode including a plurality of spaced conducting flat ring-shape plates all at one potential having one or more radial fluid transmitting passages therebetween, an inner electrode including a plurality of spaced flat annular plates all at one potential disposed inside of the outer electrode and having a radial fluid transmitting passage therebetween, means for establishing an are between the opposed edges of the two electrodes, means for rotating the are around the opposed peripheries of the two electrodes, and means for forcing a blast of fluid through one radial fluid transmitting passage of one electrode, longitudinally of the rotating are 8. In a circuit interrupter oi the fluid blast type, an outer electrode including a plurality of spaced conducting ring-shaped plates all at one potential having one or more radial fluid transmitting passages therebetween, an inner electrode including a plurality of spaced annular plates all at one potential disposed inside or the outer electrOde having a radial fluid transmitting passage therebetween, means for establishing an are between the opposed edges of the two electrodes. means for rotating the are around the opposed peripheries of the two electrodes, means for forcing a blast of fluid through one radial fluid transmitting passage of one electrode longitudinally of the rotating arc and then out through one radial fluid transmitting passage of the other electrode, and the spacing between the spaced plates of the said other electrode being between Va and 1': inch.

ALBERT P. S'I'ROM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,947,230 Ruppel Feb, 13, 1934 2,103,121 Slepian Dec. 21, 1937 2,125,525 Thommen Aug. 2, 1938 2,193,238 Ramsey 1. Mar. 12, 1940 2,306,186 Rankin Dec. 22, 1942 2,333,598 Strom Nov. 2, 1943 FOREIGN PATENTS Number Country Date 429.997 Great Britain June 11, 1935 

